<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Promise基本语法</title>
</head>
<body>
  <script>
    //实例化 Promise 对象
    const p = new Promise (function(resolve,reject){
      setTimeout(function() {
        //
        // let data = '数据库中的用户数据';
        // //resolve
        // resolve(data);

        let err = '数据读取失败';
        reject(err)
      }, 1000);
    }) 

    //调用 promise 对象的  then 方法
    p.then(function(value){
      console.log(value); 
    },function(reason){
      console.error(reason);
    })
  </script>
</body>
</html>